Upgrade protobuf-java to 3.6.1

Change-Id: Iaa8d69eb1e7be784863f0a1540f28b6e94f27fa8

WORKSPACE

diff --git a/WORKSPACE b/WORKSPACE
index b7e6659..ed31535 100644
--- a/WORKSPACE
+++ b/WORKSPACE
@@ -116,8 +116,8 @@
 
 maven_jar(
     name = "protobuf",
-    artifact = "com.google.protobuf:protobuf-java:3.5.1",
-    sha1 = "8c3492f7662fa1cbf8ca76a0f5eb1146f7725acd",
+    artifact = "com.google.protobuf:protobuf-java:3.6.1",
+    sha1 = "0d06d46ecfd92ec6d0f3b423b4cd81cb38d8b924",
 )
 
 maven_jar(